| Objective:This study was to compare the plasma cortisol and 24h urinary free cortisol responses obtained with 1μg and 50μg short ACTH stimulation tests in healthy adults. To settle the theory basis for optimizing the dose of ACTH in the dynamic test for the purpose of diagnosing mild adrenocortical insufficiency.Methods:40 Healthy adults (20F,20M) with normal circadian rhythm were recruited.The exclution criteria were allergic constitution,pregnancy,lactation,suffering from severe hypertention, diabetes mellitus,infection,gastric ulcer, osteoporosis, hypokalemia psychological diseases,or have any disease that affects HPA axis,adrenal or thyroid gland or to be on exogenous glucorticoid or other drugs that may affect HPA axis. The fasting blood glucose,serum kalium, plasma cortiol of 8am and 4pm,serum level of free triiodothyronine,free thyroxine,TSH,creatinine and transaminases, ECG, ophthalmotonus, routine analysis of blood, urine and feces were measured before dynamic tests and found to be in the normal ranges. all participants signed the written informed consent.The subjects underwent 1μg and 50μg short ACTH stimulation tests consecutively on 2 days,24 hours urines were collected from 8am to the next 8am on the day before test and the 2 days performing the tests to measure free cortisol respectively. an indewelling venous cannula were placed into one forearm at 7am on the first day,after seating quietly for at least 30 minutes, stimulation test were started at 8am with the i.v. injection of 1μg ACTH on day 1 and 50μg ACTH on day 2, blood samples for cortisol determination were taken from the i.v. cannule at baseline and 15,30,60,120 and 180 (for 50μg stimulation test only)minutes after the administration of ACTH, cortisol level was measured using a chemiluminiscence immunoassay. The analysis of variance for repeated measures, Student's t-test and wilcoxon test were completed by using SPSS 17.0.Results:(1) 40 healthy subjects (20F,20M),medium age 24 years, completed 1μg and 50μg stimulation tests.(2) In the 1μg stimulation test, peak value of plasma cortisol was 795.3±143.4nmol/L, urinary free cotisol value wasl.2±0.7 times of the basal one.(3) In the 50μg stimulation test, peak value of plasma cortisol was 1083.4±144.3nmol/L, urinary free cotisol value was5.2±0.9 times of the basal one,dizziness,nausea and some other symptoms were reported by 33 subjects after injection of 50μg ACTH.(4) There were no difference between basal plasma cortiol levels in both tests. plasma cortiol levels of 15,30,60,120minutes and values of urinary free cortiol were greater in 50μg stimulation tests. (5) The peak plasma response did not differ significantly between different sex groups.Conclution:(1) Both of the peak plasma levels of cortisol in the rapid 1μg and 50μg rapid ACTH stimulation test reached the level of severly stressed state.Compared with the 50μg test, The plasma and urinary cortisol response were lower in the 1μg rapid ACTH stimulation test,and the side effects were rare in thel gμrapid stimulation test.(2) The 1μg rapid stimulation test may be regarded as a better test for screening mild adrenocortical insufficiency. |
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